Murder, Suicide, and Protection: Investigating Cyanide as a Weapon in History and the Natural World Carolyn Starz 6/25/2010 In this set of lessons, students will be introduced to natural selection by studying cyanide, a chemical with potentially lethal effects. Cyanide is best known as a suicide pill. Made infamous by its use in WWII in the suicides of Hitler and his closest companions, cyanide capsules are still used and portrayed in popular media (e.g., the television program “24”) as a method of suicide. In the 1980‘s, tampered Tylenol laced with cyanide also caused the deaths of a handful of people in Chicago. Cyanide can kill when ingested or inhaled, though as a chemical weapon it is not as effective as others (such as mustard gas) which kill or incapacitate at much lower doses. Cyanide is an intriguing chemical to study in biology for several reasons. First, while cyanide has whole-body effects (like death!), it acts on only one enzyme, cytochrome c oxidase, in the human body. This enzyme is located in the electron transport chain of mitochondria, organelles students know as eukaryotic cells’ powerhouses. When cyanide inhibits this enzyme, aerobic cellular metabolism grinds to a halt, ATP production ceases, and tissue death begins. If exposure levels are high enough, death can occur in less than ten minutes. Second, students may be familiar with cyanide’s presence in the natural world, and if they aren’t they will certainly be intrigued by learning that this highly toxic chemical is present in some of their favorite fruits. Most people know its not good to eat peach pits or apple seeds, though few could tell you that these fruits, and other stone fruits, have cyanide in their seeds. In fact, many plants have used cyanide as an effective defense mechanism against predation. This set of lessons includes an introduction to cyanide in which students are presented with a fragmented story about the Goebbels children, who were murdered using cyanide in Hitler’s bunker during the invasion of Berlin. Students then research the lethal chemical and teach their classmates about its chemistry, uses, mechanism of action, and sources. Students then work through a case study covering the basics of natural selection, evolution, and fitness which focuses on cyanide in two variants of white clover (adapted from a study published by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York). These lessons are aligned with the South Carolina Science Standards. Carolyn Starz June 2010 © Stage 1—Desired Results Established Goals: The student will demonstrate an understanding of how scientific inquiry and technological design, including mathematical analysis, can be used appropriately to pose questions, seek answers, and develop solutions (South Carolina Science Stardard B-1). The student will: • 1.1 Generate hypotheses • 1.4 Design scientific investigations that utilize controls, independent and dependent variables. • 1.5 Organize and interpret data • 1.6 Evaluate experimental results and hypotheses The student will demonstrate an understanding of the flow of energy within and between living systems (SCSS B-3). The student will: • 3.3 Recognize the structure of ATP and summarize its function The student will demonstrate an understanding of biological evolution and the diversity of life (SCSS B- 5). The student will: • 5.1 Summarize the process of natural selection Understandings: Students will understand that . ATP is required to power essential life functions Cyanide disrupts cellular metabolism The disruption of processes at the cellular level can cause whole-body disruption, even death The prevalence of an organism in a specific environment is related to it’s fitness The length of the arms on a phylogenetic tree is related to the relationship between its organisms Essential Questions: What are some notable instances in which cyanide has been used by humans in the past? Is cyanide an effective chemical weapon? How and why are plants living in colder climates different from those living in warmer climates? Why do some plants contain cyanide? How have plants adapted to contain cyanide in response to their environment? How does cyanide cause death? Could cyanide affect anaerobic organisms? Students will know . The basic structure of ATP The general mechanism by which cyanide prevents the formation of ATP (interfering with enzymes in the electron transport chain) Specific vocabulary related to the unit, including: Natural selection, fitness, artificial selection, adaptation, survival of the fittest, descent with modification, natural variation, evolution, common descent, Carolyn Starz June 2010 © Students will be able to . Explain the concept of fitness using clover as an example Effectively search the internet for information by evaluating sources and refining searches Read, understand, and synthesize data presented in figures and tables Predict the distribution of organisms (clover) with different adaptations in specific habitats Formulate hypotheses regarding the fitness of organisms with various adaptations in specific environments Design experiments (including data collection) to test hypotheses, focusing on only one variable at a time Synthesize and summarize knowledge gained about natural selection, adaptation, evolution, and variation from the clover case study Stage 2—Assessment Evidence Performance Tasks: • Researching cyanide activity, discussion, and teaching. Students will demonstrate effective search techniques and research skills and will then, in groups, teach their classmates about an aspect of cyanide or cyanide poisoning. • Exercises 1-10 from clover case study Other Evidence: • Gallery walk story/description, initial and revised • Quiz including questions on cyanide’s characteristics and effects (drawn from students’ presentations on day 1), natural selection and evolution, and skills/information related to the case study Stage 3—Learning Plan Materials: Gallery walk photos Der Spiegel Article Movie Der Untergang Laptops with internet access Library books containing information about cyanide Cyanide research questions Whiteboard and markers Student sheets from case study Case study introduction Day 3 Homework Natural Selection Powerpoint Natural Selection Figures Optional: examples of striped and plain white clover Carolyn Starz June 2010 © Learning Activities: Day One - “Hook” and Introduction to Cyanide 1. Begin class with a gallery walk of the last days in Hitler’s bunker in Berlin, including Goebbel children’s murder and Eva Braun’s suicide, both by cyanide capsules (15 min.) a. Have students walk through the gallery of pictures and view them in order. b. Ask students to write a one paragraph story describing what they thing is happening. 2. Have students read an excerpt from an article on the murder/suicides from the German newspaper Der Spiegel. When students have finished, have them view the scene in which the Goebbel children are given cyanide from the movie Der Untergang . 3. Have students rewrite their description from part 1.b., drawing from information in the article/video. 4. Explain to students that they will be studying cyanide, the chemical used to murder the Goebbel children, Hitler, and his wife Eva Braun. Cyanide is often associated with capsules used in suicides like those of Hitler and his entourage, but it occurs in nature and students may encounter it in their everyday life. The class will spend the next ten minutes or so researching cyanide using laptops and relevant library books provided. a. Optional technology tutorial: If necessary, demonstrate effective internet search techniques, including refining searches for more specific, in depth information based on general sources (e.g. Wikipedia) using a laptop and projector. b. Divide students into groups of 3-4 and have each group get a laptop and several books. Every student should be actively researching and writing down key information, though if they are on task, up to two students may be working on the computer together. 5. After students have researched for 5-10 minutes, instruct them to get together and share what they found with their other group members. The group should summarize this information and answer one of the following question sets, assigned to their group by the teacher and given to them on a slip of paper: a. Cyanide’s chemistry: List the chemical formulas for at least 3 cyanide compounds and describe the bonds that hold them together (hint: more than one type!). What ion do they all contain? List and briefly explain 3-4 uses of cyanide. b. Make a list of as many naturally occurring sources of cyanide as you can. What characteristics do these sources share? How are they different? c. Cyanide’s effects 1: List and briefly explain the symptoms of cyanide poisoning. Define any words you don’t know in your explanation (e.g., to explain a symptom of the condition hypothermia, one could say: “One symptom of hypothermia is tachycardia, or a faster than normal heartbeat). What is “cyanosis,” and is it a symptom? Why/why not? d. Cyanide’s effects 2: Explain the mechanism by which cyanide causes death first at the level of the entire organism and second at the level of the cell and its organelles. e. Cyanide’s uses: Could cyanide be used effectively as a chemical weapon in a war? Explain why or why not. Might cyanide be more effective as a method of suicide? Explain. 6. Have each group select a representative to share their response to their question and instruct the other students to take notes from what each group says. If needed, take notes on the board to assist ELL students or to simply model note-taking methods. Carolyn Starz June 2010 © a. After the last group has finished, write the following on the board: “Poison is in everything, and no thing is without poison. The dosage makes it either a poison or a remedy.” b. Ask a student to rephrase the quote as he or she understands it (this saying, attributed to Paraclesus, is often rephrased as “The dose makes the poison”).